Unconventional superconductivity arised from screened coulomb interaction in twisted bilayer graphene

Po Jui Chen^1*, Chung Yu Mou¹

¹Dpartment of Physics, National Tsing Hua University, Hsinchu, Taiwan

* Presenter:Po Jui Chen, email:jeff991807@gmail.com

Twisted Bilayer Graphene(TBG) serves as an ideal platform to realize many exotic phenomena such as superconductivity or correlated insulating states. Inspired by experimental observation for the superconducting phase, it is important to explore the superconducting mechanism in TBG. Here, we consider the effect of long-range Coulomb interaction, with the correction by screening. Furthermore, we consider the valley, sublattice, and layer index as pseudo-spin degrees of freedom when defining superconducting order parameters. By solving mean field gap equations for all possible scenarios, we determined which pairing configuration is the most dominant and obtain the critical temperature which is close to experimental data. In addition, we also tuned electron doping and interaction strength to show how the dominance of superconducting pairing and the critical temperature depends on these parameters. Our theory provides a complete description of cooper wavefunction when TBG is in the superconducting phase.

Keywords: twisteed bilayer graphene, coulomb interaction, superconductivity